Hydraulic cylinder latch

ABSTRACT

Elongated resilient member comprised of materials having different spring rates. One end thereof is fixed to the cylinder, and the other extends out over the rod such that an arcuated portion is capable of engaging the rod.

United States Patent [1 1 Hershman et al.

[ Feb. 5, 1974 HYDRAULIC CYLINDER LATCH [75] Inventors: Gordon L. Hershman, La Grange; Wilbur E. Schwerdtfeger, Western Springs, both of I11.

[73] Assignee: Internationl Harvester Company,

Chicago, Ill.

22 Filed: Nov. 16, 1972 21 Appl. No.: 307,307

[52] US. Cl 92/26, 92/30, 188/67, 267/159 [51] Int. Cl. FlSb 15/26 [58] Field of Search 92/15, 25, 26, 30; 188/67;

[5 6] References-Cited UNITED STATES PATENTS Parsons et al 251/297 X 3,466,008 9/1969 Kitazawa 251/297 Primary Examiner-Edgar W. Geoghegan Assistant ExaminerAbraham Hershkovitz Attorney, Agent, or Firm-John A. Schaerli; Floyd B. Harman 5 7] ABSTRACT Elongated resilient member comprised of materials having different spring rates. One end thereof is fixed to the cylinder, and the other extends out over the rod such that an arcuated portion is capable of engaging the rod.

6 Claims, 3 Drawing Figures 7 of the hydraulic cylinder in a retracted position.

The increased demand for building and construction work has obviously created an increased demand for equipment capable of performing the required functions. However, such equipment is costly and to some degree cumbersome and difficult to transport. Thus in order to avoid the expense of new and additional equipment a builder will transport construction equipment from one job site to another. As stated earlier because of the nature of the equipment such transportation creates problems not associated with normal on the job routine work orientated tasks. For the most part construction equipment such as backhoes for example, are operated by hydraulic cylinder means. That is, hydraulic cylinder means are used to actuate the bucket, dipper stick and boom etc. Additionally, because of the increased size of such equipment it becomes necessary to fold or transport it in a tight package such to clear underpasses, wires and in general not create a hazard on the public thoroughfare. The builder must therefore purchase equipment which has these capabilities or adapt his existing equipment such that it can be folded or compacted and then locked in place. For the most part such locking in place or holding down is achieved through the use of chains, ropes etc. which are bulky cumbersome to use and time consuming in attaching and removing. Further, some construction equipment is simply not adaptable to be tied down to the use of such means. This tied down problem becomes even more critical in the case of hydraulically actuated means. For example, in the transportation of a loader backhoe mounted on a vehicle it is quite simple to drive the vehicle onto a truck bed and then actuate the respective hydraulic cylinders to fold the backhoe assembly into a compact unit. This technique would for all practical purposes solve the problem if it were not for the fact that hydraulic cylinders have a tendency to leak. That is for one reason or another fluid leaks from the high pressure side to the low pressure side with the subsequent extension/retraction of the cylinder rod. As is apparent such relaxing of the hydraulic cylinders while the assembly is being transported can lead to enumerable difficulties.

Accordingly, it is an object of this invention to provide a latch means which will automatically lock a cylinder rod in a retracted position.

Still another object of this invention is to provide a latch which is easily adaptable to existing hydraulic cylinders.

It is another object of this invention to provide a latch which requires more force to unlatch than latch.

Still another object of this invention is to provide a latch wherein the amount of force necessary to latch and unlatch is adjustable.

Accordingly this invention provides an improved latch means which automatically locks and unlocks a retracted. push rod of a hydraulic cylinder. The latch includes a series of elongated resilient means, one end thereof being mounted to the hydraulic cylinder. housing the other end being curved. The top resilient strip means has a higher spring rate than that of the lower and a smoother end curve. The lower: strip has a lower spring rate and the end curve is more pronounced and carries a tab which extends backwardly contacting the lower surface of the upper curved end. Together these curves constitute a catch which cooperate with the pusher rod to securely lock it in place. A securing means is movably mounted on the strips and can be fastened to lock the strips together thereby changing their relative spring rate. Additionally an ear or projection can be formed on the pusher rod to cooperate with the catch such that a stronger lockup can be achieved.

The preferred embodiment of this invention is illus- FIG. 3 is an expanded view of the latch shown in FIG.

1 showing the action of the locking forces involved. Turning first to FIG. 1 there is shown a hydraulic cylinder means 10; which includes a housing means 12 and a rod means 14. The rod means 14 has a boss or eye means 16. The operation of hydraulic cylinder means 10 as well as the other components involved with the assembly are well known in the art and therefore no further discussion will be directed thereto.

The removable latch means 18 includes a series of elongated resilient means such as first and second means 20 and 22. In the preferred embodiment first and second resilient means are metal strips each being substantially flat and lying in an abutting relationship for a substantial amount of their respective lengths. The first end means 24 of the elongated resilient means 20 and 22 are secured to a support means 26 whereby they are supported on cylinder housing 12. As is apparent any type of support means would be sufficient, however, in the preferred embodiment support means 26 is a block member welded to housing 12. Elongated resilient means 20 and 22 extend substantially parallel to rod means 14 out beyond cylinder end 28 such that a locking relationship can be achieved with said rod means 14. The resilient metal strips 20 and 22 have different spring rates, that is first strip 20 which overlies second strip 22 has a greater spring rate than underlying strip 22. The second end means30 and 32 include arcuated portions 34 and 36. Arcuated section means 36 is provided with a concaved inner surface 38 which grips or engages the rod means. Further, arcuated section 36 is provided with a tab means 40 which bends back from the direction of curvature to a point adjacent the bottom concave surface 42 of arcuated means 34. As is apparent from a consideration of FIGS. 1 and 2 the curve or bend in arcuated means 36 is greater than that in arcuated means 34. The purpose for this as well as the difference in spring rates of the elongated member means will be hereafter made more clear.

Further according to the invention, the latch member 18 is constructed in a manner so that less force is required for the engaging step than during the disengaging step. As will become more apparent from a considerationof FIGS. 2 and 3, during the latching step only resilient means 22 is involved. Looking at FIG. 3, as catch means 44 is pushed to the right it engages first tab means 40 which in turn transfers force to and along arcuated section 38 due to the noncompressibility of elongated resilient means 22 the curve along arcuated section 38 increases such that point 46 moves upwardly while point 48 pivots downwardly. As stated previously elongated resilient means 22 has a lower spring rate than that of elongated means 20. Once the means 44 has moved sufficiently to the left point means 46 slides down over the surface thereof thereby providing a pocket or single jaw in conjunction with arcuated section 38.

Referring now to FIG. 2 and assuming the operator wishes to extend push rod means 14, force will be delivered to catch means 44 which in turn will be transferred to arcuated portion 38. As the force against arcuated section 38 increases it is deflected outwardly that is the curve becomes less and tab means 48 abuts the concaved surface 42 of arcuated section 34. Force is thereby transmitted up to act against elongated resilient means 22 which due to its greater spring rate resists the outward passage of catch means 44.

It is thus apparent that the force required to secure the rod means 14 is less than that required to extend it. As a result, a very positive latching effect is achieved.

An additional feature of this invention is the movable securing means 50 as shown in FIG. 2. The purpose of this movable means is to allow the spring rate of elongated resilient means 22 to be varied within limitations. That is, during the locking procedure as shown in FIG. 3 if the total length of elongated resilient means 22 was free and available for bending a bump or knee might be forced up somewhere therealong instead of having the bend along arcuated section 38. By fastening elongated means 22 to elongated means 20 at some desired position such as securing means 50, it becomes possible to keep all of the bend along articulated section 38 or to allow some of it to form in a knee along the length of the resilient member.

Although the resilient latch means has been described as made of metal, it is apparent that other materials such as resilient plastic, could be employed in a manufacture of the latch. Thus it is apparent that there has been provided, in accordance with the invention, a resilient latch means that fully satisfies the objects, aims, and advantages set forth above. While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications, and variations as fall within the spirit and broad scope of the appended claims.

What is claimed is:

1. A hydraulic cylinder means having a push rod reciprocating therein and a latch means for releasably engaging and securing said push rod when in a retracted position said latch means comprising:

first and second elongated resilient means having an abutting parallel relationship, each means having arcuated end means, said arcuated end of said sec- 0nd elongated resilient means having a greater curve than that of said first elongated means and a bend portion contacting said first arcuated end means;

a supporting means securing said first and second elongated resilient means to said cylinder means; and

a fastening means holding said elongated resilient means together.

2. The hydraulic cylinder as defined in claim 1 wherein:

said first elongated resilient means has a greater spring rate than said second elongated resilient means; and

said push rod means carries a catch means for engaging said second arcuated end means only whereby the position of the catch means is such that for unlatching said push rod the combined spring rates of said first and second resilient means must be overcome while for latching said push rod only said spring rate of said second resilient means must be overcome.

3. A hydraulic cylinder means having a push rod reciprocating therein and a latch means releasably engaging and securing said push rod when in a retracted position said latch means comprising:

first and second elongated resilient means having a parallel adjacent relationship and arcuated section means interacting with said push rod, said first elongated means having a higher spring rate than second elongated means; a connecting means securing said first elongated means to said second elongated means; and a mounting means securing said elongated resilient means to said cylinder means. 4. The hydraulic cylinder means as defined in claim 3 wherein:

said second elongated means is positioned between said first elongated means and said cylinder means, and said arcuated sections are located adjacent said push rod. 5. The hydraulic cylinder means as defined in claim 3 wherein:

said arcuated section means of said first elongated means is less curved than said arcuated section means of said second elongated means, and said second arcuated section means has a bent end portion extending toward said first arcuated section means. 6. The hydraulic cylinder means as defined in claim 5 wherein:

said push rod means includes a catch means which engages said second arcuated section means. 

1. A hydraulic cylinder means having a push rod reciprocating therein and a latch means for releasably engaging and securing said push rod when in a retracted position said latch means comprising: first and second elongated resilient means having an abutting parallel relationship, each means having arcuated end means, said arcuated end of said second elongated resilient means having a greater curve than that of said first elongated means and a bend portion contacting said first arcuated end means; a supporting means securing said first and second elongated resilient means to said cylinder means; and a fastening means holding said elongated resilient means together.
 2. The hydraulic cylinder as defined in claim 1 wherein: said first elongated resilient means has a greater spring rate than said second elongated resilient means; and said push rod means carries a catch means for engaging said second arcuated end means only whereby the position of the catch means is such that for unlatching said push rod the combined spring rates of said first and second resilient means must be overcome while for latching said push rod only said spring rate of said second resilient means must be overcome.
 3. A hydraulic cylinder means having a push rod reciprocating therein and a latch means releasably engaging and securing said push rod when in a retracted position said latch means comprising: first and second elongated resilient means having a parallel adjacent relationship and arcuated section means interacting with said push rod, said first elongated means having a higher spring rate than second elongated means; a connecting means securing said first elongated means to said second elongated means; and a mounTing means securing said elongated resilient means to said cylinder means.
 4. The hydraulic cylinder means as defined in claim 3 wherein: said second elongated means is positioned between said first elongated means and said cylinder means, and said arcuated sections are located adjacent said push rod.
 5. The hydraulic cylinder means as defined in claim 3 wherein: said arcuated section means of said first elongated means is less curved than said arcuated section means of said second elongated means, and said second arcuated section means has a bent end portion extending toward said first arcuated section means.
 6. The hydraulic cylinder means as defined in claim 5 wherein: said push rod means includes a catch means which engages said second arcuated section means. 